<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    //symbol创建
    let s = Symbol()
    console.log(s, typeof s)

    let s1 = Symbol('shangguigu')
    let s2 = Symbol('shangguigu')
    console.log(s1 === s2)
    //symbol.for()创建
    let s3 = Symbol.for('shangguigu')
    let s4 = Symbol.for('shangguigu')
    console.log(s3 === s4)

    //不能与其他数据类型运算

    //js数据类型 USONB
  </script>
</body>
</html>